X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Fstrstr.m4;h=779957aac93e801e00ee61762103592c7dd0089c;hb=5a9eb938fe7692fef0c13fb6bccda9c2a80db224;hp=5a49b07c2c4abcbf220e60386fa94b41c89e9e23;hpb=b6d1202a37101d586919b49c8d0531b5bb56d4a3;p=gnulib.git

diff --git a/m4/strstr.m4 b/m4/strstr.m4
index 5a49b07c2..779957aac 100644
--- a/m4/strstr.m4
+++ b/m4/strstr.m4
@@ -1,16 +1,29 @@
-# strstr.m4 serial 2
-dnl Copyright (C) 2008 Free Software Foundation, Inc.
+# strstr.m4 serial 7
+dnl Copyright (C) 2008, 2009, 2010 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
 
-dnl Check that strstr is efficient.
-AC_DEFUN([gl_FUNC_STRSTR],
+dnl Check that strstr works.
+AC_DEFUN([gl_FUNC_STRSTR_SIMPLE],
 [
   AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
-  AC_CACHE_CHECK([whether strstr works in linear time],
-    [gl_cv_func_strstr_linear],
-    [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+  AC_REQUIRE([gl_FUNC_MEMCHR])
+  if test "$gl_cv_func_memchr_works" != yes; then
+    REPLACE_STRSTR=1
+    AC_LIBOBJ([strstr])
+  fi
+]) # gl_FUNC_STRSTR_SIMPLE
+
+dnl Additionally, check that strstr is efficient.
+AC_DEFUN([gl_FUNC_STRSTR],
+[
+  AC_REQUIRE([gl_FUNC_STRSTR_SIMPLE])
+  if test $REPLACE_STRSTR = 0; then
+    AC_CACHE_CHECK([whether strstr works in linear time],
+      [gl_cv_func_strstr_linear],
+      [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+#include <signal.h> /* for signal */
 #include <string.h> /* for memmem */
 #include <stdlib.h> /* for malloc */
 #include <unistd.h> /* for alarm */
@@ -20,25 +33,47 @@ AC_DEFUN([gl_FUNC_STRSTR],
     void *result = 0;
     /* Failure to compile this test due to missing alarm is okay,
        since all such platforms (mingw) also have quadratic strstr.  */
+    signal (SIGALRM, SIG_DFL);
     alarm (5);
     /* Check for quadratic performance.  */
     if (haystack && needle)
       {
-	memset (haystack, 'A', 2 * m);
-	haystack[2 * m] = 'B';
-	haystack[2 * m + 1] = 0;
-	memset (needle, 'A', m);
-	needle[m] = 'B';
-	needle[m + 1] = 0;
-	result = strstr (haystack, needle);
+        memset (haystack, 'A', 2 * m);
+        haystack[2 * m] = 'B';
+        haystack[2 * m + 1] = 0;
+        memset (needle, 'A', m);
+        needle[m] = 'B';
+        needle[m + 1] = 0;
+        result = strstr (haystack, needle);
       }
     return !result;]])],
-      [gl_cv_func_strstr_linear=yes], [gl_cv_func_strstr_linear=no],
-      [dnl pessimistically assume the worst, since even glibc 2.6.1
-       dnl has quadratic complexity in its strstr
-       gl_cv_func_strstr_linear="guessing no"])])
-  if test "$gl_cv_func_strstr_linear" != yes; then
-    REPLACE_STRSTR=1
+        [gl_cv_func_strstr_linear=yes], [gl_cv_func_strstr_linear=no],
+        [dnl Only glibc >= 2.9 and cygwin >= 1.7.0 are known to have a
+         dnl strstr that works in linear time.
+         AC_EGREP_CPP([Lucky user],
+           [
+#include <features.h>
+#ifdef __GNU_LIBRARY__
+ #if (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 9) || (__GLIBC__ > 2)
+  Lucky user
+ #endif
+#endif
+#ifdef __CYGWIN__
+ #include <cygwin/version.h>
+ #if CYGWIN_VERSION_DLL_MAJOR >= 1007
+  Lucky user
+ #endif
+#endif
+           ],
+           [gl_cv_func_strstr_linear=yes],
+           [gl_cv_func_strstr_linear="guessing no"])
+        ])
+      ])
+    if test "$gl_cv_func_strstr_linear" != yes; then
+      REPLACE_STRSTR=1
+    fi
+  fi
+  if test $REPLACE_STRSTR = 1; then
     AC_LIBOBJ([strstr])
   fi
 ]) # gl_FUNC_STRSTR